Oligomeric proanthocyanidin helps in cancer treatment by inhibiting the initiation and progress of cancer cells. This is why according to a study, it was found that Jobelyn water extract had a stronger effect on increasing Cluster of Differentiation 69 expression in Natural Killer cells (higher cytotoxic activity) while Jobelyn Ethyl Alcohol extract had the greatest effect on increasing Cluster of Differentiation 69 expression in Natural Killer T-cells, T-cells and monocytes (activation & proliferation). In addition to its selective cytotoxicity property, oligomeric proanthocyanidin may up-regulate certain apoptosis promoter genes and down-regulate apoptosis-inhibitor genes in cancerous cells.